The invention relates to the technical field of self-lubricating hinge connections, in particular in respect of mounting a shaft in a bushing or bearing, for the purpose of translatory and/or rotational guidance.
The invention is used to advantage in the case of hinge connections that operate in an abrasive medium.
In an abrasive medium, the wear phenomenon may sometimes be highly significant. Said wear may become apparent on the shaft and/or the bushing and is the result of external attack generally at the point of contact of the outside diameter of the shaft with the inside diameter of the bushing or bearing.
In an attempt to resolve this problem, a proposal has been made for the bore of the bushing or bearing under consideration to be fitted with at least one leak-tight protective joint, in order to try to ensure that the hinge connection continues to operate properly in an abrasive medium. More often than not, the body of the bushing is made of metal, whereas the added joint may be made of PU, PA, NBR, etc. For example, the joint may be mounted in a counterbore formed coaxially to the bore of the bushing.
Still with the objective of creating a leak-tight protective barrier against external attack, a bushing solution is clearly stated in the teaching in the document WO 2005/072387 which relates to a bushing fitted with an added joint housed in a counterbore formed at each of the ends of the bore of the bushing. Each joint is shaped to create a leak-tight barrier.
But it has turned out that the fact of adding a joint relative to the bushing, on the one hand, and the fact that the joint is made out of a different material from that of the bushing, on the other hand, present some drawbacks. For example, there may be risks of the joint being dislodged. The fact that the hinge connection is composed of heterogeneous parts, in terms of materials, may generate dimensional variations, further in particular to phenomena of expansion in terms of the differentials between the components, humidity absorption, resumption of tightening etc.
It is also observed that, according to the prior art, a plurality of materials are in contact with the shaft or the conflicting parts, namely the metal in respect of the bushing and the material of the joint. The result is that the wear is not uniform.
Lastly, these added joints generate a not inconsiderable cost given the number of parts required and occasional assembly difficulties.
The set purpose of the invention is to overcome these drawbacks in a straightforward, safe, effective and rational manner.
The problem the invention sets out to resolve is that of providing anti-abrasion protection in the case of a hinge connection against any type of external attack, without the necessity of adding an additional joint, as is apparent in the prior art analysis.